The variation of water vapour near the Martian surface will
be influenced by exchange with the subsurface, condensation
on the surface and in the atmosphere, mixing between the
boundary layer and the free atmosphere, and the large-scale
horizontal mixing of air masses. In order to isolate column
processes from those of transport, we have developed a
“complete” model of column water cycling based around a
one-dimensional version of the Martian Weather Research and
Forecast (WRF) model. Explicitly treated processes include
subsurface water diffusion and adsorptive/condensational
exchange, surface ice formation, diffusive mixing in the
atmosphere, and the microphysics of atmospheric cloud/fog
formation and sedimentation. The formation of surface ices
and clouds/fogs allow for the activation of feedback systems
due to their influence on the radiative heating of the
surface and hence the surface energy balance and
temperature. The model is used to assess the variation of
cloud/fog vertical structure and water vapour at likely
Phoenix and MSL landing sites (for which fog and water
vapour measurements, respectively, are planned for
collection). The implication of cloud radiative effects for
retrieval of surface thermal properties will also be
discussed.